Turbulence and Diapycnal Mixing in Drake Passage

Direct measurements of turbulence levels in the Drake Passage region of the Southern Ocean show a marked enhancement over the Phoenix Ridge. At this site, the Antarctic Circumpolar Current (ACC) is constricted in its flow between the southern tip of South America and the northern tip of the Antarcti...

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Bibliographic Details
Main Authors: L. St. Laurent, A. C. Naveira Garabato, J. R. Ledwell, A. M. Thurnherr, J. M. Toole, A. J. Watson
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Published: 2012
Subjects:
Antarctic
Antarctic Peninsula
Drake Passage
Southern Ocean
The Antarctic
Antarc*
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.294.2071
http://www.noc.soton.ac.uk/soes/staff/acng/JPO_StLetal12.pdf
Description
Summary:Direct measurements of turbulence levels in the Drake Passage region of the Southern Ocean show a marked enhancement over the Phoenix Ridge. At this site, the Antarctic Circumpolar Current (ACC) is constricted in its flow between the southern tip of South America and the northern tip of the Antarctic Peninsula. Observed turbulent kinetic energy dissipation rates are enhanced in the regions corresponding to the ACC frontal zones where strong flow reaches the bottom. In these areas, turbulent dissipation levels reach 10 28 Wkg 21 at abyssal and middepths. The mixing enhancement in the frontal regions is sufficient to elevate the diapycnal turbulent diffusivity acting in the deep water above the axis of the ridge to 1 3 10 24 m 2 s 21. This level is an order of magnitude larger than the mixing levels observed upstream in the ACC above smoother bathymetry. Outside of the frontal regions, dissipation rates are O(10 210)Wkg 21, comparable to the background levels of turbulence found throughout most mid- and low-latitude regions of the global ocean. 1.

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